Atyphoon is atropical cyclone that develops between180° and100°E in theNorthern Hemisphere and which produces sustained hurricane-force winds of at least 119 km/h (74 mph).[1] This region is referred to as theNorthwestern Pacific Basin,[2] accounting for almost one third of the world's tropical cyclones. The termhurricane refers to a tropical cyclone (again with sustained winds of at least 119 km/h (74 mph)) in the north central and northeast Pacific, and the north Atlantic.[3] In all of the preceding regions, weaker tropical cyclones are calledtropical storms. For organizational purposes, the northernPacific Ocean is divided into three regions: the eastern (North America to140°W), central (140°W to 180°), and western (180° to 100°E). TheRegional Specialized Meteorological Center (RSMC) for tropical cyclone forecasts is inJapan, with other tropical cyclone warning centres for the northwest Pacific inHawaii (theJoint Typhoon Warning Center), thePhilippines, andHong Kong. Although the RSMC names each system, the main name list itself is coordinated among 18 countries that have territories threatened by typhoons each year.[4]
Within most of the northwestern Pacific, there are no official typhoon seasons as tropical cyclones form throughout the year. Like any tropical cyclone, there are several main requirements for typhoon formation and development. It must be in sufficiently warmsea surface temperatures, atmospheric instability, highhumidity in the lower-to-middle levels of thetroposphere, have enoughCoriolis effect to develop alow pressure centre, a pre-existing low level focus or disturbance, and a low verticalwind shear. Although the majority of storms form between June and November, a few storms may occur between December and May (although tropical cyclone formation is very rare during that time). On average, the northwestern Pacific features the most numerous and intense tropical cyclones globally. Like other basins, they are steered by thesubtropical ridge towards the west or northwest, with some systems recurving near and east ofJapan. The Philippines receive the brunt of the landfalls, withChina and Japan being less often impacted. However, some of the deadliest typhoons in history have struck China. Southern China has the longest record of typhoon impacts for the region, with a thousand-year sample via documents within their archives.Taiwan has received the wettest known typhoon on record for the northwest Pacifictropical cyclone basins. However, Vietnam recognises its typhoon season as lasting from the beginning of June through to the end of November, with an average of four to six typhoons hitting the country annually.[5][6]
According to the statistics of the Joint Typhoon Warning Center, from 1950 to 2022, the Northwest Pacific generated an average of 26.5 named tropical cyclones each year, of which an average of 16.6 reached typhoon standard or above as defined by the Joint Typhoon Warning Center.[7]
Typhoon may trace to風癡 (meaning "winds which long last"), first attested in 1124 in China. It was pronounced as[hɔŋtsʰi] inMin Chinese at the time, but later evolved to [hɔŋ tʰai]. New characters風颱 were created to match the sound, no later than 1566.[8][9] The word was introduced toMandarin Chinese in the inverted Mandarin order颱風[tʰaɪfɤŋ], later picked up by foreign sailors to appear as typhoon.[8] The usage of颱風 was not dominant untilChu Coching, the head of meteorology of thenational academy from 1929 to 1936, declared it to be the standard term.[10][11] There were 29 alternative terms for typhoon recorded in a chronicle in 1762, now mostly replaced by颱風,[12] although風癡 or風颱 continues to be used inMin Chinese- andWu Chinese- speaking areas fromChaozhou, Guangdong toTaizhou, Zhejiang.[8]
Some English linguists proposed the English word typhoon traced to the Cantonese pronunciation of颱風[tʰɔifuŋ] (correspond to Mandarin[tʰaɪfɤŋ]), in turn the Cantonese word traced to Arabic.[13] This claim contradicts the fact that the Cantonese term for typhoon was風舊[fuŋkɐu] before the national promotion of颱風.[8]風舊 (meaning "winds which long last") was first attested in 280, being the oldest Chinese term for typhoon.[9] Not one Chinese historical record links颱風 to an Arabic or foreign origin.[10][11] On the other hand, Chinese records consistently assert foreigners refer typhoon as "black wind".[10][11] "Black wind" eventually enters the vocabulary ofJin Chinese as黑老風[xəʔlofəŋ].[14]
Alternatively, some dictionaries propose that typhoon derived from (طوفان)tūfān, meaning storm inPersian andHindustani.[15][16] Theroot of (طوفان)tūfān possibly traces to the Ancient Greek mythological creatureTyphôn.[16] InFrenchtyphon was attested as storm in 1504.[17] Portuguese travelerFernão Mendes Pinto referred to atufão in his memoir published in 1614.[18] The earliest form in English was "touffon" (1588),[16] later as touffon, tuffon, tufon, tuffin, tuffoon, tayfun, tiffoon, typhawn.[10][11]
Atropical depression is the lowest category that theJapan Meteorological Agency uses and is the term used for a tropical system that has wind speeds not exceeding 33 knots (38 mph; 61 km/h).[19] A tropical depression is upgraded to atropical storm should itssustained wind speeds exceed 34 knots (39 mph; 63 km/h). Tropical storms also receive official names from RSMC Tokyo.[19] Should the storm intensify further and reach sustained wind speeds of 48 knots (55 mph; 89 km/h) then it will be classified as asevere tropical storm.[19] Once the system's maximum sustained winds reach wind speeds of 64 knots (74 mph; 119 km/h), the JMA will designate the tropical cyclone as atyphoon—the highest category on its scale.[19]
Since 2009 theHong Kong Observatory has divided typhoons into three different classifications:typhoon,severe typhoon andsuper typhoon.[20] Atyphoon has wind speed of 64–79 knots (73–91 mph; 118–149 km/h), a severe typhoon has winds of at least 80 knots (92 mph; 150 km/h), and a super typhoon has winds of at least 100 knots (120 mph; 190 km/h).[20] TheUnited States'Joint Typhoon Warning Center (JTWC) unofficially classifies typhoons with wind speeds of at least 130 knots (67 m/s; 150 mph; 241 km/h)—the equivalent of a strong Category 4 storm in theSaffir-Simpson scale—assuper typhoons.[21] However, the maximum sustained wind speed measurements that the JTWC uses are based on a 1-minute averaging period, akin to the U.S.'sNational Hurricane Center andCentral Pacific Hurricane Center. As a result, the JTWC's wind reports are higher than JMA's measurements, as the latter is based on a 10-minute averaging interval.[22]
There are six main requirements for tropical cyclogenesis: sufficiently warm sea surface temperatures, atmospheric instability, highhumidity in the lower to middle levels of thetroposphere, enoughCoriolis force to develop a low pressure center, a pre-existing low level focus or disturbance, and low vertical wind shear. While these conditions are necessary for tropical cyclone formation,they do not guarantee that a tropical cyclone will form. Normally, an ocean temperature of 26.5 °C (79.7 °F) spanning through a depth of at least 50 metres (160 ft) is considered the minimum to maintain the specialmesocyclone that is the tropical cyclone. These warm waters are needed to maintain thewarm core that fuels tropical systems. A minimum distance of 500 km (300 mi) from theequator is normally needed for tropical cyclogenesis.[23]Whether it be a depression in theIntertropical Convergence Zone (ITCZ) ormonsoon trough, a broadsurface front, or anoutflow boundary, a low level feature with sufficientvorticity and convergence is required to begin tropical cyclogenesis. About 85 to 90 percent of Pacific typhoons form within themonsoon trough.[24] Even with perfect upper-level conditions and the required atmospheric instability, the lack of a surface focus will prevent the development of organized convection and a surface low. Vertical wind shear of less than 10 m/s (20 kn, 33 ft/s) between the ocean surface and thetropopause is required for tropical cyclone development.[23][25] Typically with Pacific typhoons, there are twojets ofoutflow: one to the north ahead of an upper trough in thewesterlies, and a second towards the equator.[24]
In general, the westerly wind increases associated with theMadden–Julian oscillation lead to increased tropical cyclogenesis in alltropical cyclone basins. As the oscillation propagates from west to east, it leads to an eastward march in tropical cyclogenesis with time during that hemisphere's summer season.[26] On average, twice per year twin tropical cyclones will form in the western Pacific Ocean, near the5th parallel north and the5th parallel south, along the same meridian, or line of longitude.[27] There is an inverse relationship between tropical cyclone activity in the western Pacific basin and the North Atlantic basin, however. When one basin is active, the other is normally quiet, and vice versa. The main reason for this appears to be the phase of the Madden–Julian oscillation, or MJO, which is normally in opposite modes between the two basins at any given time.[28]
Nearly one-third of the world's tropical cyclones form within the western Pacific. This makes this basin the most active on Earth.[30] Pacific typhoons have formed year-round, with peak months from August to October. The peak months correspond to that of theAtlantic hurricane seasons. Along with a high storm frequency, this basin also features the most globallyintense storms on record. One of the most recent busy seasons was2013. Tropical cyclones form in any month of the year across the northwest Pacific Ocean and concentrate around June and November in the northern Indian Ocean. The area just northeast of the Philippines is the most active place on Earth for tropical cyclones to exist.
Across the Philippines themselves, activity reaches a minimum in February, before increasing steadily through June and spiking from July through October, with September being the most active month for tropical cyclones across thearchipelago. Activity falls off significantly in November, althoughTyphoon Haiyan, the strongest Philippine typhoon on record, was a November typhoon.[31] The most frequently impacted areas of the Philippines by tropical cyclones are northern and centralLuzon and easternVisayas.[32] A ten-year average of satellite determined precipitation showed that at least 30 percent of the annual rainfall in the northern Philippines could be traced to tropical cyclones, while the southern islands receive less than 10 percent of their annual rainfall from tropical cyclones.[33] The genesis and intensity of typhoons are also modulated by slow variation of the sea surface temperature and circulation features following a near-10-year frequency.[34]
Tracks of all tropical cyclones in the northwesternPacific Ocean between 1980 and 2005. The vertical line to the right is theInternational Date Line.
Most tropical cyclones form on the side of the subtropical ridge closer to the equator, then move poleward past the ridge axis before recurving north and northeast into the main belt of thewesterlies.[35] Most typhoons form in a region in the northwest Pacific known as typhoon alley, where the planet's most powerful tropical cyclones most frequently develop.[36] When the subtropical ridge shifts due toEl Niño, so will the preferred tropical cyclone tracks. Areas west of Japan andKorea tend to experience many fewer September–November tropical cyclone impacts during El Niño and neutral years. During El Niño years, the break in the subtropical ridge tends to lie near130°E, which would favor the Japanese archipelago.[37] During La Niña years, the formation of tropical cyclones, and the subtropical ridge position, shift westward across the western Pacific Ocean, which increases the landfall threat toChina and greater intensity toPhilippines.[37] Those that form near theMarshall Islands find their way toJeju Island, Korea.[38] Typhoon paths follow three general directions.[30]
Straight track (or straight runner). A general westward path affects thePhilippines, southern China,Taiwan, andVietnam.
A parabolic recurving track. Storms recurving affect the eastern Philippines, eastern China, Taiwan, Korea, Japan, and the Russian Far East.
Northward track. From point of origin, the storm follows a northerly direction, only affecting small islands.
A rare few storms, likeHurricane John, were redesignated as typhoons as they originated in the Eastern/Central Pacific and moved into the western Pacific.
The list of names consists of entries from 14 southeast and east Asian nations and regions and the United States who have territories directly affected by typhoons. The submitted names are arranged into a list, the names on the list will be used from up to down, from left to right. When all names on the list are used, it will start again from the left-top corner. When a typhoon causes damage in a region, the affected region can request for retiring the name in the next session of the ESCAP/WMO Typhoon Committee. A new name will be decided by the region whose name was retired.
Unlike tropical cyclones in other parts of the world, typhoons are not named after people. Instead, they generally refer to animals, flowers, astrological signs, and a few personal names. However, Philippines (PAGASA) retains its own naming list, which consists of both human names and other objects.[43] Japan and some other East Asian countries also assign numbers to typhoons.[44]
Storms that cross the date line from the central Pacific retain their original name, but the designation of hurricane becomes typhoon.
List of Western Pacific tropical cyclone names(as of 2024)
The most active Western Pacific typhoon season was in1964,[citation needed] when 39 storms of tropical storm strength formed. Only 15 seasons had 30 or more storms developing since reliable records began. The least activity seen in the northwest Pacific Ocean was during the2010 Pacific typhoon season, when only 14 tropical storms and seven typhoons formed. In the Philippines, the most active season since 1945 for tropical cyclone strikes was1993, when nineteen tropical cyclones moved through the country.[46] There was only one tropical cyclone that moved through the Philippines in1958. The2004 Pacific typhoon season was the busiest for Okinawa since 1957.[47] WithinGuangdong in southern China, during the past thousand years, the most active decades for typhoon strikes were the 1660s and 1670s.[48]
The highest reliably-estimatedmaximum sustained winds on record for a typhoon was that ofTyphoon Haiyan at 314 km/h (195 mph) shortly before its landfall in the centralPhilippines on November 8, 2013.[49] The most intense storm based on minimum pressure wasTyphoon Tip in the northwestern Pacific Ocean in 1979, which reached a minimum pressure of 870 hectopascals (26 inHg) and maximum sustained wind speeds of 165 knots (85 m/s, 190 mph, 310 km/h).[50] The deadliest typhoon of the 20th century wasTyphoon Nina, which killed nearly 100,000 in China in 1975 due to a flood that caused 12 reservoirs to fail.[51] AfterTyphoon Morakot landed in Taiwan at midnight on August 8, 2009, almost the entire southern region of Taiwan (Chiayi County/Chiayi City,Tainan County/Tainan City (now merged as Tainan),Kaohsiung County/Kaohsiung City (now merged as Kaohsiung), andPingtung County) and parts ofTaitung County andNantou County were flooded by record-breaking heavy rain. The rainfall inPingtung County reached 2,327 millimeters (91.6 in),[52] breaking all rainfall records of any single place in Taiwan induced by a single typhoon,[53] and making the cyclone the wettest known typhoon.
^abChen, Shou, ed. (280). "陸凱傳".三國志·吳書 [Records of the Three Kingdoms – Book of Wu].蒼梧、南海，歲有舊風瘴氣之害，風則折木，飛沙轉石;徐兢 (1124).宣和奉使高麗圖經 [The trip of the Imperial envoy to Korea, with illustrations].海道之難甚矣...又惡三種險：曰癡風，曰黑風，曰海動。癡風之作，連日怒號不止，四方莫辨;荔鏡記 [Tale of the Lychee Mirror]. 1566.風台過了，今即會[sic, 回]南. As cited in李荣 (1990)."台风的本字(上)".方言 (4).;李荣 (1991)."台风的本字(中)".方言 (1).;李荣 (1991)."台风的本字(下)".方言 (2).
^贺雪梅 (2020). "吴堡县篇". In 王建领 (ed.).陕西方言集成:榆林卷. 商务印书馆. pp. 692–726.
^Onions, C. T., ed. (1966). "Typhoon".The Oxford Dictionary of English Etymology. Oxford University Press. p. 965.typhoon. cyclonic storm in the China seas. XVI [century]. Adoption of Chinesetai fung, dialect variant ofta big,feng wind; confer Germantaifun,teifun, Frenchtyphon. Earlier †tuffoon (XVII), identified in form with †touffon (XVI), †tuffon (XVII) violent storm in India, adoption of Portuguesetufão, adoption of Hindustani (in turn, adoption of Arabic)ṭūfān hurricane, tornado, beside which there was a contemporary † typhon (XVI), adoption of Latintȳphōn, adoption of Greektuphôn, related totūphein (see TYPHUS).
^Kam-Biu Liu; Caiming Shen; Kin-Sheun Louie (2001). "A 1,000-Year History of Typhoon Landfalls in Guangdong, Southern China, Reconstructed from Chinese Historical Documentary Records".Annals of the Association of American Geographers.91 (3):453–464.doi:10.1111/0004-5608.00253.ISSN0004-5608.S2CID53066209.
^Samenow, Jason; McNoldy Brian (2013-11-08)."Among Strongest Storms Ever".The Washington Post.Archived from the original on 2013-11-08. Retrieved2013-11-08.
